If your loudspeaker is a purely resistive load. The analysis does not address a real loudspeaker load. so like amplifier power ratings is simplistic.
dave
No, merely declaring an interest. I'm not suggesting dishonesty, but predisposition. We are all subject to that. I'm sure Ben Duncan believes what he says. Just like you do, and I do.ThorstenL said:
A calculation based on standard circuit theory might not be true? So some effect (perhaps what BD feels he has discovered) moves the points away from the Lesurf line, then another effect moves them back again? Or did Lesurf completely misunderstand or misrepresent the article? Anything is possible, I agree, but which is most likely?
It is unfortunate that there does not seem to be an online copy of the article.
That's the one; "How Long is a Piece of String?" His derivations all use a generalized Z for a load. He does some examples at the end with a simple resistance as a load, but you can use the basic equations for any impedance, and the results are still the same- a very short cable (i.e., <<< than a wavelength) can be treated by lumped parameters.
EM theory says that short cables act like lumped elements. Lesurf's calculations illustrated this for a particular resistive load. The theory is still true for any load. The illustration was for the benefit of those who think correct theory is insufficient for their needs. It is not simplistic to say that in a short distance there is insufficient time for retardation to have any significant effect. It is simply true.
One of the first things I was taught in EM classes at university is that at sufficiently low frequency (or, equivalently, sufficiently small apparatus) the lumped approximation is true. Lesurf is merely illustrating this fact.
One of the first things I was taught in EM classes at university is that at sufficiently low frequency (or, equivalently, sufficiently small apparatus) the lumped approximation is true. Lesurf is merely illustrating this fact.
You guys are missing a very important point here. There are large capacitance's in the the rooms in which these tests, both objective and subjective, are being conducted. These giant capacitors are going to have a profound effect upon any cable that does not have low proximity effect construction. And, since cables constructed in this manner have very expensive conductors you can bet they are not being used.
In addition these capacitors suffer from dielectric aging which alters their behavior. This failure with aging is often referred to as avalanche breakdown. It is a form of electric current multiplication that can allow very large currents within materials which are otherwise good insulators. It is a type of electron avalanche. The avalanche process occurs when the carriers in the transition region are accelerated by the electric field to energies sufficient to free electron-hole pairs via collisions with bound electrons.
This electron acceleration can have numerous bad effects upon the cables under test. And then there is the possibility of flash over, with attendant boil off of hot liquids and gasses from the end aperture of the capacitors, in the room with the cables. And remember, these capacitors are huge in comparison to the cables, so the effects are going to be magnified by all of the hot gases and liquids released by the avalanche process. So, until we can be certain a set of test were run in a capacitor free environment we must assign a question mark to their validity.
Bud
In addition these capacitors suffer from dielectric aging which alters their behavior. This failure with aging is often referred to as avalanche breakdown. It is a form of electric current multiplication that can allow very large currents within materials which are otherwise good insulators. It is a type of electron avalanche. The avalanche process occurs when the carriers in the transition region are accelerated by the electric field to energies sufficient to free electron-hole pairs via collisions with bound electrons.
This electron acceleration can have numerous bad effects upon the cables under test. And then there is the possibility of flash over, with attendant boil off of hot liquids and gasses from the end aperture of the capacitors, in the room with the cables. And remember, these capacitors are huge in comparison to the cables, so the effects are going to be magnified by all of the hot gases and liquids released by the avalanche process. So, until we can be certain a set of test were run in a capacitor free environment we must assign a question mark to their validity.
Bud
What Jim wrote was: (hilite mine..)
<QUOTE>
""The recorded data clearly indicates a tendency for the phase shift at high current to be significantly greater than at low current. This implies that complex audio signals traversing the cables will be subtly distorted by current-to-phase modulation effects.
Upon first reading the articles, I was prompted to wonder what other effects might have given rise to the observed phase changes. Precision measurements of the kind presented are notoriously difficult and it is prudent to view any unexpected effects as being potentially due to simple system imperfections or methodology errors. Only when these have been eliminated can we safely conclude that a radical new effect has been discovered. ""
<END OF QUOTE>
What startles me is this: given a change in load resistance, what else was changed? Were the inductances of the loads measured? Were they the same, different, did they track resistive value?
If one is measuring a cable for some effect, why in the world would someone add another length of cable to it??? And, look at the values. sheesh.
Jim wrote that the "primed" elements mean per unit length..48 milliohms for r, .6 uH for L, 350 pf for C..(I have to assume he really meant the unprimed values).. But my goodness, what kind of cable did they use???That R and C are huge.. Also, he felt it appropriate to use a t-symmetric model for this cable...."" In this case it is appropriate to model the cable run as a T-symmetric lumped arrangement as we are interested in the interaction between the resistive load and the cable under test
Forget magneto...the forces are far too small at these current levels. And, it could only produce second order harmonics, not alter primary phase.
Your statement gave the appearance of impropriety on the part of Duncan. Perhaps not your intent, but that's what it appeared to do. Isotropic would be my choice..
Agreed.
Cheers, Jn
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This discussion has been going on now for well over 3 decades. Never has any one mentioned the small fact that every one hears or perceives sound a little differently. Even our two ears respond differently.
Or how every ones rooms are different in size, shape, dampening, construction material quality and who knows what else. If you have crappy room it doesn't much matter what kind of equipment you use the sound will be crappy until the room is worked on.
Then there are the speaker issues.
To make this more challenging you have the room issues and then equipment interface issues. Then adding to this the differences in hearing between people. It is little wonder that cabling has been an issue of contention for a very long time.
The simple truth is you have to choose cabling that makes you system sound best to you. It is your system and you have to please yourself. There is always going to be snake oil sales man. The best defense is common sense and knowledge. No one cable works for all situations!
Or how every ones rooms are different in size, shape, dampening, construction material quality and who knows what else. If you have crappy room it doesn't much matter what kind of equipment you use the sound will be crappy until the room is worked on.
Then there are the speaker issues.
To make this more challenging you have the room issues and then equipment interface issues. Then adding to this the differences in hearing between people. It is little wonder that cabling has been an issue of contention for a very long time.
The simple truth is you have to choose cabling that makes you system sound best to you. It is your system and you have to please yourself. There is always going to be snake oil sales man. The best defense is common sense and knowledge. No one cable works for all situations!
That was certainly not my intention, so I'm sorry if that is how it appears. All I was trying to say is that Duncan is clearly on one side of the debate, so much so that he acts as a consultant to other people on the same side of the debate. I have no idea where he stood on this issue before he did the tests described in his article.jneutron said:
A question for anyone that posts "I hear a difference".
Could you post the polar and CSD measurements of your speaker with each cable showning those differences to me...
Posts with quotes like
Would indeed be easy to prove/validate with a simple speaker measurement using ARTA and a $100 calibrated mic/sound card setup. I mean if people are hearing the differences as plain as day then the measurement showing the speaker response change would be easy....wouldn't it??
FWIW, I have done the $3K worth of cables test from JPS Labs. I could not measure any response differences from my speakers between those speaker wires or interconnects vs quality Blue Jean Cable products. I also had 3 months of listening to try and spot the difference again nothing existed. Measurements backed up my subjective conclusions so how about it from everyone else?
Note: It was an absolute pleasure to work with JPS on the test and the cables are the best build quality I have seen. The speaker wire (superconducter 3) ?? was incredible (but stiff) and the banana clips are the best I have ever used period. I can see paying a premium for function and looks but I can not find a real audible test proving any differences.
Conclusion, speaker design (different XO choices including linear phase), speaker placement, room treatments, active control (auto EQing or similar) have a far more meaningful effect then any cable ever discussed online. From what I have seen from 99.9% of all rooms and all speakers I think people might want to consider working on improving those instead of fussing over cables
Could you post the polar and CSD measurements of your speaker with each cable showning those differences to me...
Posts with quotes like
Would indeed be easy to prove/validate with a simple speaker measurement using ARTA and a $100 calibrated mic/sound card setup. I mean if people are hearing the differences as plain as day then the measurement showing the speaker response change would be easy....wouldn't it??
FWIW, I have done the $3K worth of cables test from JPS Labs. I could not measure any response differences from my speakers between those speaker wires or interconnects vs quality Blue Jean Cable products. I also had 3 months of listening to try and spot the difference again nothing existed. Measurements backed up my subjective conclusions so how about it from everyone else?
Note: It was an absolute pleasure to work with JPS on the test and the cables are the best build quality I have seen. The speaker wire (superconducter 3) ?? was incredible (but stiff) and the banana clips are the best I have ever used period. I can see paying a premium for function and looks but I can not find a real audible test proving any differences.
Conclusion, speaker design (different XO choices including linear phase), speaker placement, room treatments, active control (auto EQing or similar) have a far more meaningful effect then any cable ever discussed online. From what I have seen from 99.9% of all rooms and all speakers I think people might want to consider working on improving those instead of fussing over cables
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Good points, There was a thread in the multi-way forum that went on for 6+ years and it was finally shutdown last year....this debate will never end period. Its like arguing religion with some.
Most who do listening tests fail to actually control them very well. People do not even realize that standing a couple of inches off from the initial spot can create a different conclusion. People move their heads, walk around and so on thinking that is the right way to make critical conclusions. Its not at all the right way to do listening tests.
Im actually a big believer in "Placebo" enduced conclusions. If buying something gives someone a better experience then more power too them. I wouldnt recommend they post that opinion/experience online because I believe opinion online should always past the objective litmus test. Meaning without measurement backup/controlled experimentation opinion pretty much can be disregarded because it will most likely have huge holes.
Loudspeakers will double in their rated voice coil impedance when used at full power. In most passive crossover designs impedance also changes with frequency. So observing level related changes in the complex load is actually reasonable.
Now as we all know (
)it turns out cable is directional and there may actually be a good reason for it. However as the artifacts that change with direction are around 170 db below loudspeaker levels, it probably is not really an issue.I do object to the simplification from circuit THEORY that reduces the cable to just LRC. There actually are other issues. But for most cable users they are not important.
Honestly, I have no idea where he stands on the issue right now.
I do know that the test methodology which ignores an added inductance, capacitance, and completely forgets the inductances of the resistive loads is a test methodology which presents "opportunities"..
Cheers, John
Well most of this is certainly over my head scientific wise but I know when dealing with guitar amps which is certainly a departure from audio amps, we concern ourselves with cable capacitance a great deal since it can bleed off the high end.
Sometimes that is desirable but most of the time not.
But since we deal with longer interconnects to and from the guitar not to mention a pedal board if used it can all add up.
Even the shielded runs inside an amp can add up and chop off high frequencies.
But then again, we want it to sound like a guitar and not like a Hi Fi.
When discussing speaker cables it seems the discussion is more focused on minutiae rather than things that make a more noticeable audio or aural effect since the aim is generally to make the system transparent and to hear the recording in as high of fidelity that is possible.
Where the budget allows of course.
What I haven't seen mentioned much is how important the separation of the two conductors is since that can and does affect capacitance.
In the big picture I guess what we have constructed is a large LCR circuit where every little bit of those properties affect the sound.
I have seen where audiophiles have used separate conductors for speaker cables verses the connected pair that is generally used by most people.
So how much does the actual capacitance of speaker cable affect the high frequencies and where does the inductance properties affect it as well?
Do these properties tend to be more audible in lower wattage systems than say, a 50w per channel amp that is turned up quite loud?
Sometimes that is desirable but most of the time not.
But since we deal with longer interconnects to and from the guitar not to mention a pedal board if used it can all add up.
Even the shielded runs inside an amp can add up and chop off high frequencies.
But then again, we want it to sound like a guitar and not like a Hi Fi.
When discussing speaker cables it seems the discussion is more focused on minutiae rather than things that make a more noticeable audio or aural effect since the aim is generally to make the system transparent and to hear the recording in as high of fidelity that is possible.
Where the budget allows of course.
What I haven't seen mentioned much is how important the separation of the two conductors is since that can and does affect capacitance.
In the big picture I guess what we have constructed is a large LCR circuit where every little bit of those properties affect the sound.
I have seen where audiophiles have used separate conductors for speaker cables verses the connected pair that is generally used by most people.
So how much does the actual capacitance of speaker cable affect the high frequencies and where does the inductance properties affect it as well?
Do these properties tend to be more audible in lower wattage systems than say, a 50w per channel amp that is turned up quite loud?
Ok, who took the Pixies out of my lab... Those were special mylar phase shift resistant capacitance pixies. I need em to test some new lead-gold-unobtainium phase resistant macro dynamic ultra-chromium coated speakers wires blessed by the the Holy Prince of Southern New Jersey.
put em back and no one gets hurt...
put em back and no one gets hurt...
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